Fusible link



Patented Feb. 27, 1923.

UNITED STATES 1,446,554 PATENT OFFICE.

EDWAJRD H. ELLISON, OF JAMESTOWN, NEW YORK, ASSIGNOR T0 MONASRCH REFILL-AIBLE FUSE (.70., OF JAMFSTOWN, NEW YORlL A CORPORATION OF NEW YORK.

FUSIBLE LINK.

To all whom it may concern:

Be it known that I, EDWARD H. ELLIsoN, a citizen of the United States,residing at Jamestown, in the county ofChautauqua, State of New York,have invented certain new and useful Improvements in F usible Links, ofwhich the following is a description, reference beinghad to theaccompanying drawing and to the figures of reference marked thereon.

This invention relates to inclosed fuses of the renewable link type andmore particularly to an improved link adapted to reduce to a minimum thevolatilization of the metal of the link on the rise of an excess ofcurrent therethrough.

Heretofore it has been proposed to detachably connect the copperterminals pro ecting into the incl0sing casing by a link having spacedportions of substantially reduced cross section so that when anexcessive current occurs, the link will fuse only at said reducedportions, the intermediate'part of said link dropping out withoutvolatilizing. Experience has shown however, that because of the uniformmelting point of such single metal fuse links, particularly when theyare of low melting point, such as zinc, the heat generated by the fusingnot infrequently is sufficient to volatilize the remainder of the link,and since the natural direction of escape of the gases is toward theends of the casing, and the path of melting follows the path of thegases, the fusing is often carried beyond the terminal connections atthe ends of the casing, either so badly fuming th m as to preclude agood electrical connec ion when a new link is to be inserted, or theconnection is so impaired as torender the fuse Worthless. Theseobjectionable features are overcome in the present invention byproviding a me tallic link between its ends, with a portion or portionsof suchv relatively low melting point as compared with the relativelyhigh melting point of the remaining metal portions of the link, that theheat generatet by the melting of such portions of relatively low meltingpoint is sufiicient to fuse the remainder of the link so that no arcing0ccurs.

Another feature of the present invention resides in arranging theportion or portions of "low melting point along the link in such amanner that the is reduced to a.

provide a link as above described having in termediate its ends a seriesof metallic sections or portions of uniform cross section unlted to eachother and to the link ends by interfolding the ends of said adjoiningsec tions.

These and other objects will in part be obvious and will in part behereinafter more fully disclosed.

In the drawings, which show by way of illustration, one embodiment ofthe invention:

Figure 1 is a sectional side view of my ifrlpproved link so applied to aknife blade Fig. 2 is a plan view of said link,

Fig. 3 is a section thereof, and

Fig. 4 is a perspective thereof.

The invention in general. embraces an improved link consisting of copperends and an intermediate series of metallic sections of uniform crosssection joined together and to said copper ends by interfolded seams.These metallic sections, preferably three in number, are composed ofalternate zinc and copper metal, arranged so that the zinc sections areadjacent the copper link ends with the copper section intermediate saidzinc sections. In a link of this construction, due to the substantiallylower melting point of the zinc sections, on the rise of an excessivecurrent through said link, the zinc sections will volatilize and permitthe intermediate copper section to drop out and furthermore, the meltingpoint of the outer copper link ends being substantially higher than saidadjacent inner zinc sections, the heat generated by the fusing of thelatter will be insufiicient to melt the copper link ends so that thevolatilizationis reduced to a minimum and the melting zone is isolatedfrom the terminal connections of the fuse which are kept intact.

A link constructed as above described is especially advantageous whenused in connection with an inclosing casing, not only because of theslight volatilization of the metal but also because the casing terminalswhich are generally of copper, and are detachably connected to the endsof the fusible link, are spaced from the fusible sections and are thuspreserved from the destructive efi'ects of the inner melting zone. Theprotection of these terminals in other types of links is slight becauseof the tendency of the flames and gases during fusing to escape at theends of the casing and melt the connections in their path of escape.

Referring more particularly to the accompanying drawings, the fuse isillustrated in connection with a knife blade type of fuse, but it isunderstood that it is equally applicable to any type of fuse having aninclosing casing. This inclosing casing or tube 1 is of fiber or othersuitable material and is threaded on its interior extremities to receivethe metal sleeves 2 which are provided 'on their outer ends with thethreaded portion 3 on which screw the apertured end caps 4 and 5. Thesecaps are connected with bridge pieces 6 and 7 and are adapted to centerand hold from movement the ter 1 minals 8 and 9 of any suitableconducting material of relatively high melting point, preferably copper.Inasmuch as the specific construction of the casing, the bridge pieces,

and manner of mounting the.coppertermifuse link may be renewed onblowing.

nals forms no part of the present invention, the same being claimed in aco-pending application filed by me April 27, 1920, Serial Number376,932.

Connected to the inwardly projecting ends of the copper terminals 8 and9 is the improved fusible link, comprising the terminals or end portions10 and 11 of metal of relatively high melting point, such for instanceas copper, which fuses at approxn mately 2000 F. Any desired shape maybe given to these link ends depending upon the type of fuse in which thelink is used and the manner in which it is connected to the terminals ofthe inclosing casing. In the present instance these ends 10 and 11 areslotted as at 12 and 13 to receive the bolts 14c which provide adetachable connection to the casing terminals 8 and 9 whereby tl]1[e tis clearly understood that if the link be used in a cartridge type orsocket type of fuse, the terminals will be) changed as required. Inevery instance, however, they are of metal of relatively high meltingpoint.

In order to insure the minimum volatilization of the link metal and tolocalize the fusing at the intermediate portion of the link, the same isformed intermediate its ends 10 and 11 with a series of sections orportions of metal of substantially different melting points. In thepreferred arrangement shown in Fig, 4, sections or portions 15 and 16 ofrelatively low melting point, such as zinc, which fuses at bout 787 F,are connected to these ends 10 and 11 while intermediately connected tothese portions 15 and 16 is a portion or section 17 of relatively enemaV are within the scope of this invention providing the metal of thesesections is uniform in cross sectional area. and provided that the metalsections vary substantially as to their melting points. Where thisrelation between the melting points of the'adjacent sections issubstantial, it is possible to reverse the relation of the zinc andcopper sections by providing the link between its ends with portions ofrelatively high melting point,' such as copper, and a singleintermediate portion of relatively low melting point, such as zinc. Thisconstruction is particularly successful if this intermediate zincsection is shorter than the adjacent copper sections. I

The preferred manner of interconnecting the sections or portions isshown clearly copper sections 15, 16 and 17' are' connected 'toeachother and also to the inner ends of the copper terminals 10 and 11 byinterfolding the metal as at 18. Such interfolded seams or joints, whilepreserving the uniform cross section of the metal portions in additionprovide a secure and economical connection which readily permits thezinc sections to volatilize and the intermediate sections to drop outthereby preventing further volatilizing the metal of the link. It iswithin the contemplation of this invention to interconnect thesesections of different metals in any manner which 0 will thus preservethe uniform cross section.

In a fuse link constructed as set forth the heat generated by the fusingof the zinc sections is not sutficient to volatilize the copperportions. since zinc melts at approximately 787 F, while copper fuses atabout 2000 F. Furthermore, the ends of the link being copper, thenatural tendency of the melting to follow the movement of the'escapinggases endwise of the casing is checked so that the terminal connectionsare'kept intact.

It is obvious that minor changes in the details of construction may bemade without departing from the spirit of the invention as set forth inthe appended claims;

Having thus fully described the invention, what I claim as newranddesire to secure by Letters-Patent, is

1. A fusible metallic link having metal terminals of relatively highmelting point. and intermediate spaced fusible portions of relativelylow melting point. I

2. A fusible metallic link having terminals of relatively high meltingpoint and therebetween a series of metallic portions of substantiallyuniform cross section, said series including outer sections ofrelatively low melting point, and an intermediate sec tion of relativelyhigh melting point.

3.'A fusible link including between its ends a series of metallicportions of substantially uniform cross section, said metallic portionsbeing connected to each other and to said link ends by interfoldedjoints.

4. A fusible link including between its ends, portions of relatively lowmelting point and an intermediate portion of relatively high meltingpoint.

5. A fusible link including in series be tween its ends a plurality ofzinc portions and an intermediate copper portion.

6. A fusible metallic link having copper EDWARD H. ELLISON.

